Okay, due to my current lack of funds and desire to make another NA-TURBO, I was going to put a stock Mazda turbo I have (not sure how or when i got this...) on it.
Question 1: How much can I boost in the efficiency range for this turbo (not concerned with the motor... its ported and it gots 3pc 3mm apex seals)?
Question 2: Lets talk about the 5th and 6th ports. If I'm boosting like, say, 15 PSI on a ported motor WITH a midpipe, if I hook a tube to the midpipe to open the ports at 4000 RPMS it will be worth it, no? The 5th and 6th ports WILL provide a power increase with this setup right? I heard that under high boost the 5th and 6th ports don't help... and i was curious how that worked... I was also lookin to port my intake.

 

12psi is about the limit on the stock turbo, after that it's efficiency starts to die.

The ports aren't needed. Wire them open or remove them. With boost there's absolutely no need for them. Generally you'll have your boost fast enough that you won't even have to worry about the 'low end' torque that you'll be 'missing'